#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <assert.h>

#include <math.h>

int
main(int argc, char **argv)
{
	int n;
	double x[1000], avg = 0.;
	int i;
	double result = 0.;

	scanf("%d", &n);
	for (i = 0; i < n; i++) {
		scanf("%lf", &x[i]);
		avg += x[i];
	}
	avg /= n;
	for (i = 0; i < n; i++)
		result += (x[i] - avg) * (x[i] - avg);
	result /= n;
	result = sqrt(result);
	printf("%lf\n", result);

	return 0;
}
